Conventionally, various types of packaging containers having different shapes have been used for liquid foods such as soft drinks and milk. One such packaging container is a gable-top type packaging container which has a roof-shaped top. When the gable-top type packaging container is used, a carton blank is first formed into a square tubular carton by a filling machine, and a spout is then attached to the carton. The bottom end of the carton is then sealed by mandrels to make a bottom. A liquid food is then placed in the carton having a bottom through the top opening thereof.
After the liquid food has been placed in the carton, the top portion of the carton is folded along predetermined pleat lines, and is then sealed.
FIG. 1 is a side view of a square tubular carton which is used for forming a gable-top type packaging container, FIG. 2 is a side view of a packaging container, and FIG. 3 is a perspective view of a packaging container.
In these drawings, numeral 11 denotes a square tubular carton made of a packaging material, and numeral 12 denotes a spout attached to a predetermined position of the carton 11.
A plurality of pleat lines a through f are formed on the square tubular carton 11. The carton is folded along the pleat lines a through f to form a triangular panel 15, folding panels 16, inner sealing fins 17, outer sealing fins 18, and slanting roof panels 19. After the carton is folded along the pleat lines a through f, each pair of sealant layers of the inner sealing fins 17 facing each other is fused while each pair of sealant layers of the outer sealing fins 18 facing each other is also fused, thereby forming a packaging container 13.
An object of the present invention is to solve the above-mentioned problems in the conventional sealing apparatus for packaging containers and to provide an improved sealing apparatus for packaging containers which does not produce dust from an end surface of a paper substrate, which dust would otherwise fly around.